1. Field of the Invention
This specification relates to a method for maintaining firmware of a digital protective relay and a digital protective relay performing the same.
2. Background of the Invention
A protective relay is an apparatus having a command function of cutting off a portion from a circuit when a fault state, such as short-circuit, eddy current, overcurrent or the like occurs at the corresponding portion of the circuit. There are various types of protective relays. Examples of the various types of protective relays include an undervoltage relay operating when a circuit voltage is lowered, a temperature relay for detecting a danger temperature, a power relay operating when a power level is more than a predetermined value, a distance relay for detecting a breakdown position of a power transmission line, a differential relay operating when a current ratio of primary and secondary windings of a transformer is more than a predetermined value, a ground relay notifying a ground fault of a power transmission line, and the like.
As one example of the protective relay, a digital protective relay (hereinafter, referred to as “relay”) is an apparatus for protecting an electric circuit by preventing an affection due to a breakdown fault in a manner of sensing a voltage and a current generated during operation of the electric circuit and accurately running relay elements, such as overcurrent, open phase, phase unbalance, reversed phase, overvoltage, undervoltage and the like, based on a set value and a set operating (running) time. The series of operations of the digital protective relay are enabled by a firmware. The firmware has to be upgraded to upgrade the existing functions or support added functions. A firmware downloaded from a Personal Computer (PC) is stored in a Read Only Memory (ROM) of the relay. Upon turning the relay on, a Central Processing Unit (CPU) reads out firmware codes stored in the ROM and executes the code to run the relay.
In the meantime, when a firmware for every functional module mounted in the relay is updated in the related art, a PC or laptop computer is connected to a connector (for interface) disposed in each functional module. Accordingly, assuming that n functional modules are present, n times of connection have to be executed and n*T time (here, T denotes a time spent for firmware update) is consumed.
Therefore, development of a more simplified, intelligent method for updating the firmware of the relay is required.